1. Field of the Invention
The present invention relates to a data communication apparatus using human body and a data communication module thereof, and more particularly, to a peer-to-peer data communication apparatus easily applied to a data communication field between wearable computer systems or mobile electronic devices in human body and a data communication module thereof.
2. Description of the Related Art
A human body communication is a technology of realizing a data communication using human body instead of a data communication cable, and there is one using variation of current flowing through the human body and the other using a variation of a surface electric field of the human body. Since the human body communication can precisely restrict the communication range and the other party to be communicated with, differently from a telephone communication and a wireless communication, and the human body communication has a low risk of a crossed line and a wiretap as opposed to a telephone and a wireless communication and enables a communication with naked hands. Due to these reasons, the human body communication is being vigorously researched recently.
Meanwhile, within a human body area, there are roughly two types of the data communication between mobile electronic devices such as a wired data communication and a radio frequency (RF) data communication. The wired data communication is advantageous as it is capable of carrying out a high-speed data communication without external noise interference, but has a restriction of inconvenience used within the human body and a spatial restriction. On the other hand, a personal RF data communication such as Bluetooth and Zigbee can solve the above-mentioned inconvenience and spatial restriction, but can be used in only a low-speed data communication due to a weakness of the external noise interference and a relatively large transfer error and has a problem with a battery due to a large power consumption.
In order to solve the above-mentioned problems, M. Shinagawa et al. have proposed a high-speed human body communication technique through the human body as a data transfer medium using an electrical property of the human body (M. Shinagawa et al., “A Near-Field-Sending Transceiver for Intrabody communication Based on the Electrooptic Effect”, IEEE Transactions on Instrumentation and Measurement, vol. 53, pp. 1533-1538, December 2004).
FIG. 1 is a block diagram illustrating a principle of a conventional human body communication system proposed by Shinagawa et al. As illustrated in FIG. 1, a transmitting and receiving unit 110 of a human body communication system 100 includes a pair of signal electrode 180 and a ground electrode 120 such that a ground coupling is carried out between a transmitting unit and a receiving unit through a ground below the transmitting unit and the receiving unit. The transmitting unit 112 having a transmitter circuit directly transmits a digital signal to the human body without modulation. The receiving unit 114, since intensity of an electric field generated in the human body is very weak and unstable, uses an electrooptical sensor 116 to recover electric field into the digital signal in order to increase a reception sensibility. Using this method, the high-speed data communication through the human body is enabled, but an external sensor such as the electrooptical sensor 116, difficult to be made in the form of an integrated chip, and the ground electrode 120 are required so that it is difficult to minimize the data communication apparatus and the power consumption is increased. In other words, this method has a difficulty in minimization and achieving low power consumption.